Color photography



Patented Dec. 15, 1942 UNITED STATES PATENT OFFICE COLOR PHOTOGRAPHYLeopold D. Mannes, Rochester, N. Y., and Leopold Godowsky, Jr.,Westport, Conn., assignors to l Eastman Kodak Company, Rochester, N. Y.,a v corporation of New Jersey Application January 19, 1940, Serial No.314,689

In Great Britain January 23, 1939 14 Claims.

vtype which is Widely used commercially involves the coupling of a colorforming compound with' a primary aromatic amino developing agent to forma colored image. The coupling compounds used in this process are thosehaving a reactive methylene group or a reactive' phenolic group whichcouples with the oxidation product of the primary aromatic aminodeveloping agent on photographic development. Suggestions have been madefor incorporating these coupling compounds either in the developingsolution or in the sensitive layer before exposure.

When the coupling compounds are incorporated in the developing solution,it is desirable that they be as soluble `as possible in the developingsolution so that upon photographic development they will penetrate thegelatin or other colloidal material of the sensitive layer and therebypermit the formation of a dye image in any exposed portion of the layer.However, when the coupling compounds are to be incorporated in thesensitive layer prior to exposure, they should be insoluble in orderthat they do not wander out of the layer during coating of a multi-layermaterial or during photographic development. Methods have been proposedfor keeping the coupler, compounds in the photographic layer, most ofthese involving the use of large molecules of coupler to preventdiffusion.

In U. S. Patent 1,055,155, March 4, 1913, Fischer describes amulti-color process using coupling compounds incorporated in thephotographic layers. However, it has since been found that the couplingcompounds known to Fischer could not be kept in the respective layers ofa multi-layer material by merely mixing them with the gelatin of theemulsion'. All of the compounds disclosed by Fischer diiuse from thelayer and no color separation can be obtained in Fischers process.

We have discovered a method for incorporating coloring materials such ascoupling compounds in a photographic layer or layers so that they do notdiffuse from the layer or layers but may be made to react with theoxidation product of an aromatic amino developing agent to form acolored image or colored images on photographic development. Our methoddoes not in- A volve the use of large coupler molecules, since thecouplers which we propose to use, if merely mixed with a gelatine-silverhalide emulsion, would dilluse from the emulsion when used in amultilayer coating.

Our method consists in surrounding or mixing the coloringv material,such as a coupling compound, with a water-insoluble but water permeablecellulosic binder and then dispersing this l material in a colloidalmaterial such as gelatin. For example if the coupler is mixed with acellulose ester such as cellulose'nitrate and this mixture is thendispersed in gelatin, there is little or no tendency for the coupler todiffuse from the cellulosic material into the gelatin. This is true evenwhen the coupler is quite alkali-soluble and couplers can, therefore, beemployed which have hitherto been regarded as unsuitable forincorporation in photographic layers veither because of the readiness oftheir diffusion or because of the readiness of dilusion of dyes formedfrom them on photographic development. The coupling compounds with thecellulosie binder can best be suspended in the gelatin or other Waterpermeable material by means of an organic solvent which is immisciblewith water and, therefore, it is possible to use couplers which areextremely insoluble in aqueous alkaline solution and Whose veryinsolubility in aqueous solutions hitherto made it diilicult toincorporate them in materials such as gelatin. In some cases the use ofa water-miscible solvent, such as alcohol, induces crystallization orwandering of the coupler, and for this reason it is frequently desirableto use water-immiscible solvents in dissolving the coupler. Y

In the accompanying drawing the gures represent enlarged sections ofphotographic nlm made according to various modifications of ourinvention.

According to the present invention, there is provided a photographicelement having a plurality of differentially color sensitivephotographic emulsions on a single support. at least one suchphotographic emulsion containing a' coupling compound dispersed in awater-insoluble but water-permeable material. The elemeni-l may have aplurality of layers of diierentially color-sensitive emulsions on asingle support, one at least of which layers consists of a dispersion ofa water-insoluble but water-permeable binder containing a couplingcompound in a gelatine-silver halide emulsion.

In the preferred modification of our invention, the photographic elementmay have an emulsion consisting of silver halide in gelatin, the gelatinhaving distributed therein finely dispersed particles ofwater-insoluble. water-permeable binder containing the couplingcompound. A plurality of layers may be coated in this way eachcontaining in the water-insoluble, water-permeable. cellulosic binder acoupling compound corresponding in a suitable manner to the sensitivityof the layer. For example, for the usual three-layer photographicelement` a red sensitive photographic emulsion would be chosencontaining a blue-green coupling compound, a green-sensitive emulsioncontaining a magenta coupling compound and a blue-sensitive emulsioncontaining a yellow coupling compound.

In another modification of our invention the cellulosic particlesthemselves may contain the silver halide as well as the couplingcompound. In this modification of our invention particles of cellulosicbinder may be prepared each containing the appropriate coupling compoundand properly sensitized silver halide grains and these may be separatelydispersed in a plain gelatin layer s that a single layer element isobtained in which three differently colored images may be formed.Obviously the color sensitizer, where one is employed, is included withthe silver halide in any case.

' The water-insoluble, water-permeable cellulosic binder used tosurround the particles of coupler may be a cellulose ester, such ascellulose nitrate or cellulose acetate, or a mixed organic ester ofcellulose. such as cellulose acetate phthalate. Cellulose ethers mayalso be used. Collodion solutions, well known in the photographic art.may also be employed.

We have found that the cellulosic binders, a1- though they prevent thediffusion of the coupler into adjacent water soluble layers, that isinto the gelatin, are suillciently accessible to the developing andother processing baths to enable the usual methods of color processingto be applied. By our method, therefore, known coupler compounds may beincorporated in photographic layers and the layers may be processed inthe ordinary way. If desired, the color processing baths may containingredients such as organic solvents or wetting agents to facilitate thepenetration into the water soluble binder.

We have found that different coloring materials and coupler compoundsare respectively more suitable for use with diierent cellulosic bindersand that with some combinations of coupling compound and cellulosicbinder there is diillculty in obtaining satisfactory dye densities.This, we believe to be due to the diiculty of penetration of some of thecellulosic binders by the processing solutions. We have found that thestructure or character of the cellulosic particles may be altered byincorporating in the cellulosic solution before dispersion substanceswhich we shall call porosity modifiers. These materials change theporosity or consistency of the cellulosic material in the final statewhich it attains in the dried coating and enable better penetration ofthe photographic processing baths without inducing diffusion of thecoupler. The following materials have been found suitable for thispurpose:

Etherls Ethylene glycol monobenzyl ether Diethylene glycol monobutylether Diethylene glycol monobutyl ether monoacetate Diethylene glycolmonoethyl ether Diethylene glycol diethyl ether Ethylene glycolmonophenyl ether.

phthalate eaters Dimethyl phthalate Dibutyl phthalate Benzyl phthalate-Ethoxyethyl phthalate Alcohols Heptadecanol N-hexanol Octyl alcoholMiscellaneous esters Benzyl benzoate Triphenyl phosphate Tricresylphosphate Ethyl palmitate Methyl abietate -Ethoxyethyl sebacate-Ethoxyethyl maleate -Ethoxyethyl adipate Ethylene glycol dilaurateMiscellaneows compounds p-Toluenesulfonanilide Tripropionin TrivalerinMonoacetin Triacetin These modifiers may be used in amounts ranglngfrom` 5% to 50% of the amount of cellulosic material.

Porosity may be effectively decreased by hardening with chromium salts,particularly where cellulose acetate is used as the water-insoluble,water-permeable binder.

I'he following examples which are illustrative only, indicate variousmethods of forming sensitive photographic layers for color photographyaccording to our invention.

Example 1 An emulsion is m-ade by preparing a solution of the followingingredients:

r N-butyi acetate cc 1ooo This solution is mixed with the following:

Gardinal (fatty alcohol sulfate) g-- 2 1/z Water *n cc-- 1250 'I'hewhole mixture is heated on a steam bath at C. with constant stirring toevaporate all of the butyl acetate and some lof the water. At the end ofthe evaporation process the volume has been reduced to about 300 cc.'I'his dispersion of cellulose nitrate particles containing the coupleris added to 1000 cc. 'of a red-sensitive gelatino-silver halideemulsion. The resulting emulsion is coated on a suitable support. Ayellow lter layer is then coated on the emulsion, consisting oftartrazine in gelatin.

'I'he top layer consists of a green-sensitive silver halide gelatinemulsion to which has been added a cellulose nitrate dispersion made asdescribed in the preceding paragraph, but using as the coupler a mixtureyielding an orange-red dye upon development. Suitable .couplers for thispurpose are n-propyl-pbenzoyl acetamino benzene sulfonate and2-cyanoacetylnaphthalenesulfon-N-methyl anilide. These couplers are usedin the amount of 5 grams each and producing an orange red dye upondevelopment in a couplingy developer. 'I'his emulsion is coated as thetop layer to produce a two-layer sensitive material.

In place of the tartrazine iilter dye, the film may contain a yellow dyethroughout the emulsions which is removable during processing either byvirtue of its solubility or its susceptibility to a chemical action ofone of the processing baths.

Example 2 A three-layer sensitive film is made as follows: The bottomlayer consists of a red-sensitive gelatine-silver. halide emulsion towhich has been added a dispersion of cellulose nitrate containing, as abluegreen coupler, 5phenoxy acetamino-l-naphthol, made as described inExample 1. The middle layer is a green-sensitive gelatino-silver halideemulsion with a cellulose nitrate dispersion containing as a magentacoupler 2cyanoacetylnaphthalene-sulfon-N-methylanilide. Over the greensensitive layer is coated a thin intermediate layer containing a yellowillter material which is removed during processing, such as colloidalsilver in gelatin. The top layer is unsensitized silver halide emulsioncontaining Y as a yellow coupler w-benzoylacet-o-chloranilide andcellulose nitrate dispersion made as in Example 1.

The amount of coupler used in these dispersions may vary over widelimits. It is found necessary to adjust the coupler concentration ineach particular case depending upon the dye density to be produced thethickness of the layers and other factors. In general the couplerconcentrations may range from about 21/9 grams kto about grams ofcoupler per liter of emulsion. The cellulose nitrate and otheringredients of the emulsion may also be Variedover a wide range,depending upon properties of the particular combination being used.

Example 3 A high speed photographic multi-layer material is made bycoating three gelatino-silver halide emulsion sensitive respectively tothe red, green and blue regions of the spectrum on a single support,each emulsion containing nely dispersed particles of collodion oranother cellulose derivative containing no silver halide but merely thecoupling compound required for that layer. For the red' sensitive layerthe coupling compound (l-naphthol-Z-carboxylic-a-naphthylide) may beused, for the green-sensitive layer the coupling compound 2-cyanoacety1lnaphthalene sulfon-N-methyl anilide may be used and for the bluesensitive layer the coupling compound benzoyl acct-2,5-dichloroanilidemay be used. 'I'hese couplers produce respectively bluegreen, magentaand yellow images upon photographic development.

The processing of this iilm may be carried out either to produce anegative image by immediate immersion in a color-forming developer or itmay be developed initially in an ordinary MQ developer or a positiveimage may be formed by exposing the :film to white light after theordinary rst development and then developing the residual halide in acolor forming developer. In either case the coupling compound remainswithin the cellulose particle into which, however, the oxidized couplingdeveloper penetrates freely in those localities where it has beenoxidized by developing the sensitive silver halide grains. A dye imageis thus built up in those cellulose particles most nearly adjacent tothe exposed silver halide grains.

Example 4 A sensitive photographic layer containing a coupler togetherwith silver halide in a cellulosic binder the whole being dispersed ingelatin was made as follows:

cc. of a commercial collodion emulsion were diluted with 20 cc. ofN-butyl acetate and this solution was then added to 100 cc. of a 0.1%solution of a higher fatty alcohol sulfate in water. This lattercompound which is sold under the trade name Gardinolis a well knowndispersing agent. To this solution there was added 0.25 gram of5-phenoxyacetamino'-l-naphthol and the mixture was then run through asmall homogenizer and was recirculated for five minutes. Subsequently itwas vacuum distilled to remove solvents employed in the preparation ofthe collodion emulsion and the butyl acetate which was added as notedabove. Prior to the removal of the solvent by vacuum, small amounts ofN-octyl alcohol were added to prevent foaming. After the volatilesolvents were removed. the suspension of iine particles in the Gardinolsolution was added to cc. of a 6% gelatin solution and these were coatedon a support. The particles of cellulosic binder thus produced werebelow 1 m/l in diameter. Upon exposure of this layer and development inan aromatic amino developing agent, a blue-green image was produced.

- Example 5 A collodion silver halide emulsion is made in the usualmanner and divided into three parts A, B and C. To A and B are addedrespectively suitable quantities of non-water-soluble red and greensensitizers, for example, pinacyanol or the neothiazolocarbocyaninederived' from. 2,4-dimethyl thiazole ethiodide for the red, anderythrosin for the green. To A, B and C, respectively, are addedsuitable quantities of coupling compounds which, with a developer suchas diethyl-p-phenylene-diamine, will yield blue-green, magenta andyellow dye images. Suitable compounds are 5,7-dibromo-8-hydroxyquinolinefor blue-green, p-phenylbenzoyl acetonitrile for the magenta and-naphthoyl acetone for the yellow. At this stage there are three batchesof collodion, silver halide emulsion differentially light-sensitive andcapable of forming differently colored images. Sensitizers and couplersare contained in true solution in the organic solvents used for thecollodion.

An aqueous gelatin solution is then prepared and maintained at a pH lowenough to prevent dissolving the coupling components. To this gelatinare added in substantially equal quantities minutedried particles of thethree collodionemulsions which have been spray dried or otherwisedispersed. These particles will be about the size of ordinary negativeemulsion grains but each will contain a number of exceedingly ne silverhalide particles suspended in the collodion and in intimate contact withthe sensitizing dye and coupling compound.

After suitable mixture of the dispersed particles, the gelatin carriercontaining them is coated as a single layer ona photographic support. Onexposure and development in a single developer such asdiethyl-p-phenylenediamine this layer forms three differently coloredimages.

Example 6 The following example illustrates the dispersion of anoriginally colored material in a cellulosic compound, in agelatino-silver halide emulsion.

A solution is prepared containing 20 grams of cellulose nitrate, 10grams of ethylene glycol monobenzyl ester, 10 grams of benzene azocresol and 750 cc. of butyl acetate. This solution is emulsifled, forexample, by homogenization with 1000 cc. of a 0.2% aqueous solution of ahigher fatty alcohol sulfate. The emulsion is heated with stirring toexpel the butyl acetate and the remaining iine suspension of dyedcellulose nltrate particles are added to 1000 cc. of a gelatine.

silver halide emulsion containing 6.5% gelatin.

Numerous coupler compounds are suitable for use in our invention wherethe photographic layer is designed to be developed with an aromaticamino developing agent. As stated above, couplers may be used whichwould not be suitable for incorporating in a. gelatin emulsion withoutthe use of some special means to prevent diffusion. The couplers whichwe may use have a molecular size and shape such that, although capableof diffusing through gelatin, they are readily rendered non-diiusing byphysically combining them with a dispersed cellulosic material.

The following couplers are suitable for use in our invention. It 1s tobe understood that this list is not intended to be exhaustive, butmerely to typify compounds which may be used.

Couplers producing cyan images 2,2 dihydroxy-5,5 -dibromostilbenep,p'Di-(2 hydroxybenzamido) diphenylmethane Sebacic aciddi-(2-hydroxyanilide) 1-naphthol-5-sulfo-cyclohexylamine1-naphthol-Z-carboxylic-a-naphthalidediamylnaphthalenesulfonamido-1naphthol5diphenylethersulionamidol-naphthol 5-phenoxyacetamino-1-napl1thol5-amyldiphenylethersulfonamidol-naphthol 2,4 dichlorc-4-lp-nitrobenzoyl--hydroxyethylamino] -l-naphthol Couplers producingmagenta images 1,4-phenylene bis-3(l-phenyl-5-pyrazolone)2cyanoacetylnaphthalenesulfon N methylanilide 2-cyanoacetylcoumarone5-sulfon-N-methylanilide 2-cyanoacetylcoumarone-5-sulfondimethylamide2-cyanoacetyl-5benzoylaminocoumarone 2cyanoacetyl--naphthofuranCyanoacet--naphthalide Couplers producing yellow images N -phenyl-N-(p-acetoacetaminophenyl) urea p.p'DiacetoacetaminodiphenylmethaneBenzoylacet2,5-dichloranilide N,N' -di- (w-benzoylacetyl) -p-phenylenediamine N,Ndi(p-benzoylacetaminophenyl)naphthaiene-1,5-disulfonamide p,p'-Di(acetoacetaminmdiphenyl 4 .4 -diacetoacetamino) 3,3'dimethyldiphenyl Our invention will now be describedwith particular reference to the accompanying drawing. As shown in Fig.1, a support I0 of any suitable material such as cellulose nitrate orcellulose acetate, synthetic resin, or paper, is coated with a plaingelatin layer II .and a plain gelatin layer I2 each containing dispersedparticles oi' a suitable water permeable but water insoluble cellulosicbinder. Emulsion layer I2 contains the cellulosic particles I3containing coupler A and silver halide. Gelatin layer II containsdispersed particles Il of cellulosic material containing coupler B andsilver halide. It is to be understood that the silver halide isdispersed in the cellulosic particle and that the coupler is dissolvedin it, and that the drawing is not intended to indicate that the silverhalide and the coupler occupy concentric portions in the cellulosicparticle.

As shown in Fig. 2, the support I0 is coated with gelatino silver halideemulsion layers I5, I6 and I1 sensitive respectively to the red, greenand blue regions of the spectrum. Emulsion layer I'I contains cellulosicparticles I8 containing coupler A', emulsion layer I6 containscellulosic particles I9 containing coupler B' and emulsion layer I5 hasdispersed therein cellulosic particles 20 containing coupler C'. 'I'heblue, green and red sensitive silver halide particles in the respectiveemulsion layers are represented by numerals 2|, 22 and 23.

Fig. 3 shows a support I Il containing a gelatin layer I I containingdifferentially sensitized particles of cellulosic binder. 2l is aparticle of cellulosic binder containing coupler A' and silver halidegrains, 25 is a particle of cellulosic binder containing coupler B' andsilver halide grains sensitized to another region of the spectrum and 26is a particle of cellulosic binder containing couplers C' and silverhalidel grains sensitized to a third region of the spectrum.

The method of preparing, exposing and developing these various types ofphotographic element will be understood from referring to the specificexamples above.

Our invention is susceptible of numerous var iations not hereinspeciiically described and it is to be understood that our invention islimited only by the scope of the appended claims.

We claim:

l. A light-sensitive layer for producing a colored image, comprising agelatino-silver halide emulsion containing ilnely divided particles of awater-insoluble but water-permeable cellulose ester containing a colorformer in physical mixture therewith, dispersed in the gelatin.

2. A light-sensitive layer for producing a colored image, comprising anemulsion of silver halide in a water-soluble, water-permeable colloidalmedium, said emulsion containing finely divided particles of awater-insoluble but waterpermeable cellulose ester containing a colorformer in physical mixture therewith, dispersed in the water-soluble,waterpermeable colloidal medium.

3. A light-sensitive element for producing a colored image, comprising alayer of a waterpermeable silver halide-colloidal medium havingdispersed therein finely-divided particles of a water-insoluble butwater-permeable cellulose ester containing a color-former in physicalmixture therewith.

4. The method of producing a color-forming photographic layer, whichcomprises mixing a water-insoluble but water permeable cellulosecompound in an organic solvent with a colorforming compound capable oireacting with a primary aromatic amino developing agent on :giotcgraphicdevelopment, dispersing the mixture of cellulose compound andcolor-forming compound in a gelatino-silver halideemulsion, and coatingsaid dispersion on a support.

5.. The method of producing a color-forming photographic layer, whichcomprises mixing a water-insoluble but water permeable cellulose nitratewith a color-formingl compound capable of reacting with a primaryaromatic amino.. developing agent on photographic development,dispersing the mixture of cellulose nitrate and color-forming compoundin a gelatino-silver halide emulsion, and coating said dispersion on asupport.

6. The method of producing a color-forming photographic layer, whichcomprises mixing a water-insoluble but water-permeable cellulose acetatewith a color-forming compound capable of reacting with a primaryaromatic amino developing agent on photographic development, dispersingthe mixture of cellulose acetate and color-forming compound in agelatine-silver halide emulsion, and coating saiddispersion on asupport.

'1. The method of producing a color-forming photographic layer, which'comprises mixing with a water-insoluble but water-permeable cellulosecompound a porosity modifier for the material and a color-formingcompound capable 'of reacting with a primary aromatic am'ino developingagent on photographic development, dispersing the mixture of cellulosecompound and colorforming compound in a gelatino-silver halide emulsion,and coating said dispersion on a support.

8. The method of producing a color-forming photographic layer, whichcomprises mixing with a water-insoluble hut water-permeable cellulosenitrate a porosity modier for the cellulose nitrate and a color-formingcompound capable of reacting with' a primary aromatic amino developingagent on photographic development, dispersing the mixture of cellulosenitrate and colorforming compound in a. gelatino-silver halide emulsion,and coating said dispersion on a .sup- DOrt.

9. The method of producing a color-forming photographic layer, whichcomprises mixing with a water-insoluble but water-permeable celluloseacetate a porosity modifier for the cellulose acetate and acolor-forming compound capable of reacting with a primary aromatic aminodeveloping agent on photographic development, dispersing the mixture ofcellulose acetate'and colortorming compound in a. gelatino-silvei'halide graphic development, and a porosity modier for the cellulosecompound which increases the per-7 meability of the cellulose compoundto developing solutions when incorporated in a gelatin emulsion layer,and dispersing the cellulose compound containing the color-formingcompound and porosity modifier in a gelatin layer.

11. In the method of producingv a sensitive photographic element capableof being developed to form a colored image, the steps which comprisedissolving in a water-insoluble but waterpermeable cellulose nitrate acolor-forming compound capable of reacting with a primary aromatic aminodeveloping agent on photographic development, and a porosity modier forthe cellulose nitrate which increases the permeability of the cellulosenitrate to developing solutions when incorporated in a gelatin emulsionlayer, and dispersing the cellulose nitrate containing the colorformingcompound and porosity modifier in a gelatin layer.

12. A photographic element for producing multi-'color photographicimages, comprising gelatin having dispersed therein a water-insolublebut .water permeable cellulose compound containing in separate particlesdifferent color formers in physical mixture therewith anddifferentlysensitized silver halides.

13. A photographic element for producing multi-color photographicimages, comprising a gelatin layer having dispersed therein awaterinsoluble but water-permeable cellulose ester containing inseparate particles diierent colorformers infphysical mixture therewithand differently-sensitized silver halides.

14. The method of incorporating a coupling compoundin` a light-sensitivegelatine-silver halide emulsion, which comprises dissolving it in awater-immiscible solvent and a water-insoluble but water-permeablecellulose ester, and dispersing the cellulose ester containingthecoupling compound, in the gelatino-silver halide emulsion.

LEOPOLD D. MANNES. LEOPOLD GODOWSKY. JR.

1 l cERTIFIcATE oF conBEcTioN. A. pap-,nt no. 2,5olh9ho. y December 15,1.|.2

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'gnrj vm Andale, .(su) Acting commissioner or Patente.

